Sinaia is a town and a mountain resort in Romania. The town was named after Sinaia Monastery, around which it was built; the monastery in turn is named after the Biblical Mount Sinai. King Carol I of Romania built his summer home, Peleş Castle, near the town.

Sinaia is about 60 km northwest of Ploieşti and 50 km south of Braşov, in a mountainous area on the Prahova River valley, just east of the Bucegi Mountains. The altitude varies between 767 m and 860 m.The city is a popular destination for hiking and winter sports, especially downhill skiing. Among the tourist landmarks, the most important are Peleş Castle, Pelişor Castle, Sinaia Monastery, Sinaia Casino, Sinaia train station, and the Franz Joseph and Saint Anne Cliffs. Sinaia was also the summer residence of the Romanian composer George Enescu, who stayed at the Luminiş villa.